Costs of closure within the mining sector are increasing significantly, often due to water quality that is below environmental and regulatory standards.
Problematic water quality is typically related to acid rock drainage (ARD) associated with sulfide oxidation. In many cases, perpetual collection and treatment of ARD is required too meet regulatory limits. Collection and treatment of ARD results in higher closure costs than expected and has resulted in an increased number of stranded liabilities in the industry.
The most significant sources of ARD from a mine site include mine rock stockpiles and tailings, although challenges at a mine site are site-specific. Each mine site, however, offers it’s own unique opportunities for improving post-closure water quality.
Improved techniques are being developed in the mining sector for managing closure risks at the source rather than costly collection and treatment. Okane is helping develop the site-specific methods for better managing mine rock and tailings to mitigate closure risks and decrease future uncertainties in mine closure.
Fine Tailings Management
Okane provides fine tailings management services to optimize the tailings filling rate and maximize utilization of environmental evaporation. Field monitoring of fine tailings deposits provides a base for interpretation of the tailings dewatering behaviour.
Evaporation, under-drainage, and surface runoff contribute differently to tailings dewatering for each specific tailings deposition facility. Proper interpretation of data collected from field monitoring offers a key understanding of fine tailings dewatering mechanisms. Okane’s unsaturated water flow expertise and large-strain numerical modelling greatly enhance the confidence of data interpretation, allowing the identification of major tailings dewatering mechanisms. Tailings deposition thickness can be determined in the context of the exceedance probability of achieving the desired solids content and, hence, undrained shear strength for different times of the year.